The wcc test drivers ran `ww build <bare-/tmp src>` with no -o, so the
compiler's <stem>.sepwork scratch landed beside the source and was never
cleaned: unbounded /tmp growth (2195 stale dirs observed) that fills tmpfs
and fabricates phantom test failures + silent harness aborts, and for
in-repo fixture builds leaked .sepwork into the tracked tree.
Each leaking build now writes its source + output inside a per-invocation
tmpdir, passes -o <tmpdir>/<stem> so the .sepwork lands inside it, and
rm -rf's the tmpdir on every exit path -- including fopen-fail and the
expected-fail reject builds (scratch is mkdir'd before the build can fail).
`ww run` and explicit-`-o`/byte-id helpers are left as-is; the 990/993
byte-id comparison logic is byte-for-byte unchanged.
Two items filed separately (this commit holds the no-Makefile / no-main.c
rail):
- #13: a stale <src>.s byte-id readback (749) silently no-ops since
separate-compile emits .s to <ostem>.sepwork/__root.s; documented inline.
- #14: build-system Makefile recipes build selfhost/cmd/*/main.ww with no
-o and leak main.sepwork in-tree (bounded, gitignored; own commit).
One concern -- sepwork leak hygiene -- across 228 drivers; uniform
transform applied per-file and two-round reviewed. make test: all 402
passed, zero net-new /tmp scratch, zero test-driven in-repo .sepwork.
Indexing a non-ident pointer-yielding base -- a direct cast
((&a):*[4]u32)[i], a call result mk(&a)[i], a slice, a type-assertion --
used wwstage's default 8-byte element stride/load instead of the real
element type's, reading garbage (cast-base i32 index: cs=30, ww=0). The
cgindex esz derivation gated on a whitelist of base node-kinds (DOT /
UN-deref / INDEX); an N_CAST/N_CALL/N_SLICE/N_TYPEASSERT base matched none.
Rather than extend the whitelist (whack-a-mole), this mirrors cstage's
uniform idx_eff read: N_INDEX keeps its own arm (chained-index byte-id
preserved), and every other non-ident base now derives esz/stride/load-
width/signedness from the stamped n.type_ -- closing the class by
construction (base set ident/dot/un/index/cast/call/slice/typeassert).
cstage was already correct (uniform); w6c md5 unchanged. byte-id 990-997
8/8, no lib pin flips. test/wcc/830 (9 base shapes, byte-id per width,
signed + unsigned). Folds the N_CALL sibling #22.
